Examination of an eye portion is widely performed for the purpose of preemptive medical care for lifestyle-related diseases and other diseases occupying major causes of blindness. A scanning laser ophthalmoscope (SLO) serving as an ophthalmic apparatus based on the principle of a confocal laser microscope performs raster scan on a fundus with a laser beam serving as measurement light, and quickly obtains a high-resolution planar image based on the light intensity of a return beam. Such an apparatus for capturing a planar image will be referred to as an SLO apparatus hereinafter. The planar image will be referred to as an SLO image hereinafter.
In recent years, it has become possible to obtain an SLO image of a retina with an improved lateral resolution by increasing the beam size of measurement light in an SLO apparatus. As the beam size of measurement light increases, however, the resolution and SN ratio of a planar image decrease due to the aberration of an eye to be examined in obtaining an SLO image of a retina. To solve the problem, an adaptive optics SLO apparatus including an adaptive optics for causing a wavefront sensor to measure the aberration of an eye to be examined in real time, and causing a wavefront correction device to correct the aberration of measurement light and its return beam occurring at the eye to be examined has been developed. Such an adaptive optics SLO apparatus can obtain a high-lateral resolution SLO image.
For hemodynamics, it is useful to compare and observe the blood vessel diameters and blood cell speeds of the favorite site of vascular anomalies and another site (a normal site) for diagnosis and follow-up. Since retinal vessels have symmetry in the vertical direction with respect to an optic papilla, one of means for detecting early symptoms of an eye disease is to compare the blood vessel diameters and blood cell speeds of the upper and lower portions.
In the above comparison and observation operation, to fully understand the progress of a disease, it is important to identify the positional relationship with an anatomical site/lesion or a normal site outside the imaging area of a moving image. A wide field of view image is, therefore, additionally obtained for use in the comparison and observation operation (see Japanese Patent Laid-Open No. 2010-259543 (to be referred to as literature 1 hereinafter)). Note that the blood vessel diameter or blood flow velocity may change due to a normal vital reaction such as a cardiac cycle, motion, or a change in body temperature (in addition to a change caused by a disease). To compare images captured at different imaging positions, therefore, the images need to be captured under an almost equal influence of such a vital reaction. That is, it is necessary to obtain biomedical signal data (pulse data) such as a pulse wave in capturing images, and to respectively compare blood vessel diameters and blood flow velocities with each other at the cardiac end-diastole (when the blood vessel diameter is largest, and the blood flow velocity is lowest). To compare a plurality of moving images with different imaging positions, it is necessary to avoid the influence of eye/eyelid movement such as blinking or involuntary eye movement during fixation in addition to a change due to a vital reaction, and to correct differences in image features due to a difference in imaging conditions such as a difference in aberration correction position of an imaging apparatus.
As a method of synchronously displaying a plurality of moving images under an almost equal influence of the vital reaction of an object, a technique of simultaneously displaying a plurality of diagnosis images arranged in time-series according to the cardiac pulse is described in Japanese Patent Laid-Open No. 2011-005312 (to be referred to as literature 2 hereinafter).
Literature 2, however, describes only the technique of synchronously displaying a plurality of types of moving images of the same part or moving images with different imaging times of the same part, and does not describe a technique of associating the position of the images with that on a wide field of view image. The technique described in literature 2 is an analysis/display technique for an ultrasonic diagnostic apparatus, and does not consider display adjustment which should be taken into account to display an ophthalmology image, that is, the influence of blinking or involuntary eye movement during fixation, the aberration correction position of the imaging apparatus, and the like.
Literature 1 describes a technique of superimposing and displaying the imaging area of an adaptive optics SLO image on a wide range fundus image, which is, however, processing for a single SLO image, and does not consider a technique of performing display adjustment between SLO images with different imaging positions and different imaging times.